Semiconductor device

ABSTRACT

In a semiconductor device such as a high-frequency power amplifier module, a plurality of amplifying means are formed on a semiconductor chip which is mounted on a main surface of a wiring substrate, and electrodes of the semiconductor chip are electrically connected by wires to electrodes of the wiring substrate. In order to make the high-frequency power amplifier module small in size, a substrate-side bonding electrode electrically connected to a wire set at a fixed reference electric potential is place at a location farther from a side of the semiconductor chip than a substrate-side output electrode electrically connected to an output wire. A substrate-side input electrode electrically connected to an input wire is located at a distance from the side of the semiconductor chip about equal to the distance from the side of the semiconductor chip to the substrate-side output electrode, or at a location farther from the side of the semiconductor chip than the substrate-side bonding electrode is.

RELATED APPLICATIONS

The above-referenced patent application is a continuation application ofU.S. Ser. No. 11/451,579, filed Jun. 13, 2006, now abandoned which is acontinuation application of U.S. Ser. No. 11/194,701, filed Aug. 2,2005, now U.S. Pat. No. 7,068,521, which is a continuation applicationof 10/291,840, filed on Nov. 12, 2002, now U.S. Pat. No. 6,943,441,which is a continuation of U.S. Ser. No. 09/970,668, filed Oct. 5, 2001,now U.S. Pat. No. 6,489,680, which is a divisional application of U.S.Ser. No. 09/345,505, filed Jul. 1, 1999, now U.S. Pat. No. 6,330,165.

BACKGROUND OF THE INVENTION

The present invention relates to a semiconductor device. Moreparticularly, the present invention relates to a technology effectivelyapplicable to a semiconductor device designed into a configuration of amultistage amplifier circuit.

A semiconductor device known as a high-frequency power amplifier (or ahigh-frequency power module) is incorporated in a portable communicationapparatus such as a portable telephone or a car telephone of the PDC(Personal Digital Cellular) system or a portable telephone of the PHS(Personal Handyphone System). This high-frequency power amplifier isdesigned into a configuration of a multistage amplifier circuit in whicha plurality of amplifying means are electrically connected to each otherto form a multistage structure.

The high-frequency power amplifier is built by mounting a semiconductorchip on a main surface of a wiring substrate. The semiconductor chip hasan amplifying means formed on a main surface thereof. Electrodes formedon a main surface of the semiconductor chip are electrically connectedto electrodes formed on a main surface of the wiring substrate byconductive wires. The amplifying means has a configuration in whichtypically a plurality of field-effect transistors are electricallyconnected to each other to form a parallel circuit. A gate terminal(serving as the input unit) of the amplifying means is electricallyconnected to a chip-side input electrode formed on the main surface ofthe semiconductor chip. On the other hand, a drain terminal (serving asthe output unit) of the amplifying means is electrically connected to achip-side output electrode formed on the main surface of thesemiconductor chip. The chip-side input electrode is placed at aposition on a particular side of the semiconductor chip whereas thechip-side output electrode is placed at a position on another side ofthe semiconductor chip facing the particular side. A source terminal ofthe amplifying means is electrically connected to a back-surfaceelectrode formed on a back surface of another semiconductor chip facingthe main surface. The back-surface electrode is fixed at a referenceelectric potential. The chip-side input electrode is electricallyconnected to a substrate-side input electrode formed on the main surfaceof the wiring substrate by an input wire. The substrate-side inputelectrode is placed at a position facing the particular side of thesemiconductor chip cited above. The chip-side output electrode iselectrically connected to a substrate-side output electrode formed onthe main surface of the wiring substrate by an output wire. Thesubstrate-side output electrode is placed at a position facing the otherside of the semiconductor chip cited above.

By the way, in order to reduce the size and the cost of thehigh-frequency power amplifier, an attempt has been made to form aplurality of amplifying means on one semiconductor chip. In the case oftwo amplifying means formed on one semiconductor chip, for example, theamplifying means at the front stage is oriented in a direction oppositeto a direction in which the amplifying means at the rear stage isoriented so that the input and the output of the amplifying means at thefront stage are placed at locations in close proximity to respectivelythe output and the input of the amplifying means at the rear stage. As aresult, the input and output wires at the front stage and the output andinput wires at the rear stage are close to each other. As a result,there is raised a problem of a deteriorating high-frequencycharacteristic due to a mutual-induction effect between the input andoutput wires. In particular, the mutual-induction effect between theinput wire of the front stage and the output wire of the rear stage is aserious problem since a difference between a power flowing through theinput wire and a power flowing through the output wire is big.

A technology to prevent the high-frequency characteristic fromdeteriorating due to a mutual-induction effect between wires isdisclosed for example in Japanese Patent Laid-open No. Hei 9-260412(1997). According to this technology, a chip-side bonding electrode isformed between the chip-side input electrode and the chip-side outputelectrode whereas a substrate-side bonding electrode is formed betweenthe substrate-side input electrode and the substrate-side outputelectrode. The chip-side bonding electrode is electrically connected tothe substrate-side bonding electrode and, by fixing the chip-sidebonding electrode and the substrate-side bonding electrode at areference electric potential, the high-frequency characteristic can beprevented from deteriorating due to a mutual-induction effect betweenthe input and output wires.

In addition, the high-frequency power amplifier module employingtransistors is a key device of a portable telephone of mobilecommunication adopting systems such as the PDC (Personal DigitalCellular) system and the GSM (Global System for Mobile communication).The demand for such a portable telephone has been growing tremendouslyin recent years. Specifications of such a high-frequency power amplifierinclude a small size and a low cost in addition to good high-frequencycharacteristics for applications to mobile communication systems.

A technique to respond to such a demand is disclosed in Japanese PatentLaid-open No. 2755250. By placing 2 transistors, namely, a first-stagetransistor 2000 and a second-stage transistor 3000, at locations closeto each other on a semiconductor chip 1000 as shown in a top-viewdiagram of FIG. 21 and a squint-view diagram of FIG. 22, the size andthe cost can be reduced. A bonding input electrode 2000 b of thefirst-stage transistor 2000 is electrically connected to a bondingelectrode 7000 d of a wiring substrate 6000 by an input bonding wire9000 d. A bonding output electrode 3000 c of the second-stage transistor3000 is electrically connected to a bonding electrode 7000 a of thewiring substrate 6000 by an output bonding wire 9000 a. A bondingelectrode 10000 a on the semiconductor chip 1000 is electricallyconnected to a bonding electrode 12000 a of the wiring substrate 6000 bya shield bonding wire 13000 a. The shield bonding wire 13000 a isprovided between the input bonding wire 9000 d and the output bondingwire 9000 a. The bonding electrode 10000 a and the bonding electrode12000 a at the ends of the shield bonding wire 13000 a are connected tothe ground at high frequencies by via holes bored through thesemiconductor chip 1000 and the wiring substrate. It should be notedthat the via holes themselves are not shown in the figure. By providinga shield bonding wire 13000 a, the amount of coupling through a mutualinductance between the input bonding wire 9000 d and the output bondingwire 9000 a can be reduced, allowing the degree of deterioration ofisolation between the high-frequency input and output terminals to belowered. As a result, the high-frequency characteristic is improved.

The problem of coupling through a mutual inductance between the inputbonding wire 9000 d and the output bonding wire 9000 a is raised by alocation of the input of the first-stage transistor 2000 in closeproximity to a location of the output of the second-stage transistor3000 and a location of the output of the first-stage transistor 2000 inclose proximity to the location of the input of the second-stagetransistor 3000 which are caused by the fact that the first-stagetransistor 2000 and the second-stage transistor 3000 are oriented indirections opposite to each other. In particular, the mutual-inductioneffect between the input bonding wire 9000 d of the first-stagetransistor 2000 and the output bonding wire 9000 a of the second-stagetransistor 3000 is a serious problem. This is because the high-frequencypower output by the second-stage transistor 3000 is higher than thehigh-frequency power input to the first-stage transistor 2000 by 20 to30 dB (or 100 to 1,000 times), giving rise to a positive feedback fromthe output to the input. Even though the output bonding wire 9000 c ofthe first-stage transistor 2000 and the input bonding wire 9000 b of thesecond-stage transistor 3000 are also close to each other, the problemof a deteriorating high-frequency characteristic caused by amutual-induction effect does not arise due to the fact that a ratio of ahigh-frequency power flowing through the input bonding wire 9000 b to ahigh-frequency power flowing through the output bonding wire 9000 c isnot greater than 0 dB (1 time).

In FIGS. 21 and 22, reference numerals 2000 a and 3000 a denote the mainbodies of the first-stage transistor 2000 and the second-stagetransistor 3000 respectively. Reference numerals 2000 d and 3000 ddenote the source electrodes of the first-stage transistor 2000 and thesecond-stage transistor 3000 respectively. Reference numeral 2000 cdenotes the bonding output electrode of the first-stage transistor 2000and reference numeral 3000 b denotes the bonding input electrode of thesecond-stage transistor 3000. Reference numeral 4000 denotes a groundelectrode whereas reference numerals 7000 b and 7000 c each denote abonding electrode of the wiring substrate 6000. Reference numerals 8000a to 8000 d each denote a lead electrode and reference numeral 104denotes a cavity.

SUMMARY OF THE INVENTION

As a result of a study of the technology described above, however, theinventors of the present invention identified the following problems.

The substrate-side bonding electrode is placed between thesubstrate-side input electrode and the substrate-side output elect rode.That is, the substrate-side input electrode, the substrate-side bondingelectrode and the substrate-side output electrode are laid out along astraight line beside a side of the semiconductor chip.

In general, the substrate-side electrode is formed by adopting a screenprinting technique. Thus, the area occupied by the substrate-sideelectrode is larger than the chip-side electrode which is formed byadopting a photolithography technique. In addition, a through-hole wireis formed right below the substrate-side electrode in order to make thepropagation path short. Since the area of the through-hole wire in theplane direction (that is, the external size) has to be increased to acertain degree in order to give a low resistance, the area occupied bythe substrate-side electrode becomes larger. Thus, when thesubstrate-side input electrode, the substrate-side bonding electrode andthe substrate-side output electrode are laid out along a straight linebeside a side of the semiconductor chip, the array of these electrodesis long. As a result, the chip-side input electrode and thesubstrate-side input electrode do not face each other anymore and, atthe same time, the chip-side output electrode and the substrate-sideoutput electrode also do not face each other as well. For this reason,the input and output wires become longer. When the input and outputwires become longer, the inductance increases, causing thehigh-frequency characteristic to deteriorate. As a consequence, the gapbetween the amplifying means at the front stage and the amplifying meansat the rear stage needs to be widened to make the input and output wiresshorter. In this case, however, the area occupied by the semiconductorchip increases, giving rise to a hindrance to miniaturization of thehigh-frequency power amplifier.

An effect of the shield bonding wire 13000 a of the conventionaltechnology described above is explained by referring to FIG. 15. FIG. 15is a diagram showing computed values of a coupling coefficient (or themutual inductance expressed in terms of nH) between parallel input andoutput bonding wires of an amplifier. The 2 bonding wires each have alength of 1 mm (which is close to the real thing) and have bondingportions separated from each other by a distance d. A dotted linerepresenting a coupling coefficient of 0.12 shows that the amplifieroperates in a stable state for a coupling coefficient of 0.12 orsmaller. The value 0.12 is found from FIG. 16 which shows a relationbetween the coupling coefficient and a coefficient of stability of theamplifier. The amplifier operates in a stable state for a coefficient ofstability of at least 1. The bonding distance d cited above is definedas a distance between the centers of the bonding portions of the 2bonding wires which are closest to each other.

FIG. 15 indicates that the conventional technology taking acountermeasure of providing shield bonding wires results in smallcoupling coefficients in comparison with a case with no shield bondingwires (which is denoted by a phrase ‘No countermeasure’ in the figure)and, hence, exhibits an improved high-frequency characteristic. Inaddition, for coupling coefficients not exceeding 0.12, thecountermeasure allows a wider range of the distance d between bondingportions, raising the degree of design freedom. Moreover, the distance dbetween bonding portions can be decreased to 0.55 mm, allowing the chiparea to be made smaller. As a result, the module can be made small insize and the cost can be reduced.

In actuality, however, since the inductance of a via hole is added inseries to each end of the shield bonding wire 13000 a, a sufficientimprovement of the high-frequency characteristic can not be achieved bythe conventional technology.

It is thus an object of the present invention to provide a technologythat is capable of making a semiconductor device small in size.

To be more specific, it is an object of the present invention to providea high-frequency power amplifier module that is capable of furtherimproving the high-frequency characteristic thereof.

The present invention as well as other objects and novel characteristicsthereof will become more apparent from the description of thisspecification and accompanying diagrams.

An outline of a representative of the present invention disclosed inthis patent application is described briefly as follows.

A semiconductor device comprises: a semiconductor chip having a squaresurface; a wiring substrate having a main surface thereof used formounting the semiconductor chip; a first electrode formed on a firstarea of a main surface of the semiconductor chip and placed at alocation in close proximity to a side of the semiconductor chip; firstamplifying means formed on the first area of the main surface of thesemiconductor chip and provided with an input unit electricallyconnected to the first electrode; a second electrode formed on a secondarea of the main surface of the semiconductor chip and placed at alocation in close proximity to the side of the semiconductor chip;second amplifying means formed on the second area of the main surface ofthe semiconductor chip and provided with an output unit electricallyconnected to the second electrode; a third electrode formed on a thirdarea between the first and second areas of the main surface of thesemiconductor chip; a fourth electrode formed on the main surface of thewiring substrate to face the side of the semiconductor chip andelectrically connected to the first electrode by a first wire; a fifthelectrode formed on the main surface of the wiring substrate to face theside of the semiconductor chip and electrically connected to the secondelectrode by a second wire; and a sixth electrode formed on the mainsurface of the wiring substrate to face the side of the semiconductorchip and electrically connected to the third electrode by a third wirewith an electric potential thereof fixed at a reference level,

wherein:

the sixth electrode is placed at a location farther from the side of thesemiconductor chip than the fifth electrode; and

the fourth electrode is placed at a distance from the side of thesemiconductor chip about equal to a distance of the fifth electrode fromthe side of the semiconductor chip or at a location farther from theside of the semiconductor chip than the sixth electrode. Since a gapbetween the fourth and fifth electrodes in the semiconductor chipdescribed above can be narrowed by an amount corresponding to the sizeof an area occupied by the sixth electrode, a gap between the first andsecond areas can also be made narrow as well. As a result, since thearea occupied by the semiconductor chip can be shrunk, the semiconductorchip can also be made small in size.

In addition, the objects described above can be achieved by ahigh-frequency power amplifier module having a semiconductor chipthereof provided on a wiring substrate having a base thereof made of adielectric material. The high-frequency power amplifier module isdesigned into a configuration wherein: amplifying transistors of two ormore stages, a bonding input electrode for inputting a high-frequencypower to the amplifying transistors and a bonding output electrode foroutputting a high-frequency power from the amplifying transistors areprovided on the semiconductor chip; an angle formed by a first auxiliaryline connecting bonding portions to each other at the two ends of aninput bonding wire connecting the bonding input electrode for a specificone of the amplifying transistors to the wiring substrate and a secondauxiliary line connecting bonding portions (their centers) to each otherat the two ends of an output bonding wire connecting the bonding outputelectrode for another amplifying transistor at a stage following thespecific amplifying transistor to the wiring substrate is in the range72 degrees to 180 degrees; and a gap between bonding portions of thebonding input electrode and the bonding output electrode is at least 0.3mm but smaller than 0.8 mm.

In spite of the condition stipulating that the gap between bondingportions of the bonding input electrode and the bonding output electrodeis at least 0.3 mm but smaller than 0.8 mm, the above objects can beachieved provided that the high-frequency power amplifier module isdesigned to give a coefficient of stability of at least one between thetwo amplifying transistors.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram showing a perspective view of the externalconfiguration of a high-frequency power amplifier implemented by a firstembodiment of the present invention;

FIG. 2 is an equivalent circuit diagram of the high-frequency poweramplifier;

FIG. 3 is a diagram showing a top view of principal parts of a wiringsubstrate corresponding to a portion enclosed by a single-dotted line inFIG. 2;

FIG. 4 is a diagram showing a perspective view of the principal partsshown in FIG. 3;

FIG. 5 is an enlarged diagram showing a perspective view of theprincipal parts shown in FIG. 3;

FIG. 6 is a diagram showing a cross section of principal parts in atransistor formation area of a semiconductor chip incorporated in thehigh-frequency power amplifier;

FIG. 7 is a diagram showing a cross section of principal parts in anisolation area of the semiconductor chip;

FIG. 8 is a diagram showing a top view of principal parts of a wiringsubstrate of a high-frequency power amplifier implemented by a secondembodiment of the present invention;

FIG. 9 is a diagram showing a top view of principal parts of a wiringsubstrate of a high-frequency power amplifier implemented by a thirdembodiment of the present invention;

FIG. 10 is a diagram showing a top view of principal parts of a wiringsubstrate of a high-frequency power amplifier implemented by a fourthembodiment of the present invention;

FIG. 11 is a diagram showing a top view of principal parts of atwo-stage power amplifier module implemented by a fifth embodiment ofthe present invention;

FIG. 12 is a diagram showing an equivalent circuit diagram of thetwo-stage power amplifier module implemented by the fifth embodiment ofthe present invention;

FIG. 13 is a diagram showing a top view of an external configuration ofthe two-stage power amplifier module implemented by the fifth embodimentof the present invention;

FIG. 14 is a diagram showing a perspective view of principal parts ofthe two-stage power amplifier module implemented by the fifth embodimentof the present invention;

FIG. 15 is a diagram showing curves relating a coupling coefficientbetween input and output wires to a gap between bonding portions for thepresent invention and the conventional technology;

FIG. 16 is a diagram showing a curve relating the coupling coefficientbetween input and output wires to a coefficient of stability as obtainedas a result of a study conducted by the inventors of the presentinvention;

FIG. 17 is a diagram showing a curve relating the coupling coefficientbetween input and output wires to a chip-design angle as obtained as aresult of a study conducted by the inventors of the present invention;

FIG. 18 is a diagram showing a top view of principal parts of athree-stage power amplifier module implemented by a sixth embodiment ofthe present invention;

FIG. 19 is a diagram showing a top view of principal parts of athree-stage power amplifier module implemented by a seventh embodimentof the present invention;

FIG. 20 is a diagram showing a top view of principal parts of atwo-stage power amplifier module implemented by an eighth embodiment ofthe present invention;

FIG. 21 is a diagram showing a top view of the conventional two-stagepower amplifier module; and

FIG. 22 is a diagram showing a perspective view of the conventionaltwo-stage power amplifier module.

DESCRIPTION OF THE PREFERRED EMBODIMENT

The configuration of the present invention is explained below along withembodiments applying the present invention to a high-frequency poweramplifier (high-frequency power module) incorporated in a portablecommunication apparatus such as a car telephone or a portable telephone.

First Embodiment

FIG. 1 is a diagram showing a perspective view of the externalconfiguration of a high-frequency power amplifier implemented by a firstembodiment of the present invention. FIG. 2 is an equivalent circuitdiagram of the high-frequency power amplifier. FIG. 3 is a diagramshowing a top view of principal parts of a wiring substratecorresponding to a portion enclosed by a single-dotted line in FIG. 2.FIG. 4 is a diagram showing a perspective view of the principal partsshown in FIG. 3. FIG. 5 is an enlarged diagram showing a perspectiveview of the principal parts shown in FIG. 3. FIG. 6 is a diagram showinga cross section of principal parts in a transistor formation area of asemiconductor chip incorporated in the high-frequency power amplifier.FIG. 7 is a diagram showing a cross section of principal parts in anisolation area of the semiconductor chip.

As shown in FIG. 1, in the high-frequency power amplifier implemented bythe embodiment, a cap 8 is placed on a main surface of a plane wiringsubstrate 1 to form a flat cubic structure when viewed from an externalposition. The wiring substrate 1 is built from a ceramics substrate witha multilayer wiring structure having a surface thereof formed into asquare shape (actually into a rectangular shape in the case of thisembodiment). On the other hand, the surface of the cap 8 is made from aconductive metallic material with a surface thereof formed into a squareshape (actually into a rectangular shape in the case of thisembodiment). The cap 8 is set at a fixed reference electric potential oftypically 0 [V] in order to provide a shield effect.

As shown in FIG. 2, the high-frequency power amplifier is configuredinto a multistage amplifying circuit. The multistage amplifying circuitincludes mainly capacitive elements C1 to C11, resistive elements R1 toR4, microstrip lines STL1 to STL3 and amplifying stages PW1 to PW3.

Each of the amplifying means PW1, PW2 and PW3 comprises a plurality offield-effect transistors which are electrically connected to each otherto form a parallel circuit. The amplifying means PW1 is formed with atotal extent length of the gate thereof set at about 4,000 μm and theamplifying means PW2 is formed with a total extent length of the gatethereof set at about 3,200 μm. The amplifying means PW3 is formed with atotal extent length of the gate thereof set at about 8,000 μm.

The gate terminal (serving as the input unit) of the amplifying meansPW1 is electrically connected to an input external terminal Pin to whicha high-frequency power of typically 1 [mW] is applied. On the otherhand, the drain terminal (serving as the output unit) of the amplifyingmeans PW1 is electrically connected to the gate terminal (serving as theinput unit) of the amplifying means PW2 provided at a stage followingthe amplifying means PW1 and one end of a microstrip line STL1. Further,the drain terminal (serving as the output unit) of the amplifying meansPW2 is electrically connected to the gate terminal (serving as the inputunit) of the amplifying means PW3 provided at a stage following theamplifying means PW2 and one end of a microstrip line STL2. The drainterminal (serving as the output unit) of the amplifying means PW3 iselectrically connected to an output external terminal Pout and one endof a microstrip line STL3.

The source terminal of each of the amplifying means PW1, PW2 and PW3 iselectrically connected to a reference-potential external terminal whichis set at a fixed reference electric potential of typically 0 [V]. Theother end of each of the microstrip lines STL1, STL2 and STL3 iselectrically connected to a power-supply-potential external terminalV_(DD) to which a power-supply electric potential of typically 3.5 V isapplied. It should be noted that the gate terminal of each of theamplifying means PW1, PW2 and PW3 is electrically connected to a gateexternal terminal VG. A voltage or an APC (Automatic Power Control)signal for adjusting an output power is applied to the gate externalterminal V_(G).

The amplifying means PW1 and PW2 are formed on the semiconductor chip 5shown in FIG. 3. On the other hand, the amplifying means PW3 is formedon a semiconductor chip other than the semiconductor chip 5. It shouldbe noted that the other semiconductor chip is shown in none of thefigures. The semiconductor chip 5 is mounted in a dent 1A formed on themain surface of the wiring substrate 1 whereas the other semiconductorchip is mounted in another dent formed also on the main surface of thewiring substrate 1. That is, the semiconductor chips used for creatingthe amplifying means PW1, PW2 and PW3 are mounted on the main surface ofthe wiring substrate 1. The semiconductor chip 5 and the othersemiconductor chip are each formed with a surface thereof having asquare shape (actually a rectangular shape in the case of thisembodiment). It should be noted that there will be provided no furtherdescription of the other semiconductor chip used for creating theamplifying means PW3.

As shown in FIG. 4, a conductive plate 1B is formed on the bottom of thedent 1A for mounting the semiconductor chip 5. The conductive plate 1Bis electrically connected to a reference-potential external terminal 4formed on another main surface (back surface) of the wiring substrate 1facing the main surface cited above through a through-hole wire 3 formedright below the conductive plate 1B. The reference-potential externalterminal 4 is set at a fixed electric potential of typically 0 [V]. Itshould be noted that the input external terminal Pin, the outputexternal terminal Pout, the power-supply-potential external terminalV_(DD) and the gate external terminal V_(G) are each formed on the backsurface of the wiring substrate 1.

As shown in FIG. 5, the amplifying means PW1 is formed on a first area5A of the main surface of the semiconductor chip 5. The gate terminal ofthe amplifying means PW1 is formed on the first area 5A of the mainsurface of the semiconductor chip 5 and electrically connected to achip-side input electrode 6A placed at a location in close proximity toa side 5X of the semiconductor chip 5 (one of the long sides in the caseof this embodiment). On the other hand, the drain terminal of theamplifying means PW1 is formed on the first area 5A of the main surfaceof the semiconductor chip 5 and electrically connected to a chip-sideoutput electrode 6D placed at a location in close proximity to a side 5Yof the semiconductor chip 5 (the other long side in the case of thisembodiment) facing the side 5X.

The amplifying means PW2 is formed on a second area 5B of the mainsurface of the semiconductor chip 5. The drain terminal of theamplifying means PW2 is formed on the second area 5B of the main surfaceof the semiconductor chip 5 and electrically connected to a chip-sideoutput electrode 6B placed at a location in close proximity to the side5X of the semiconductor chip 5. On the other hand, the gate terminal ofthe amplifying means PW2 is formed on the second area 5B of the mainsurface of the semiconductor chip 5 and electrically connected to achip-side input electrode 6E placed at a location in close proximity tothe side 5Y of the semiconductor chip 5.

The source terminals of the amplifying means PW1 and PW2 areelectrically connected to a back-surface electrode formed on a main backsurface of the semiconductor chip 5 facing the main surface cited above.The source terminals of the amplifying means PW1 and PW2 will bedescribed later in detail.

A third area 5C (serving as an isolation area) is formed between thefirst area 5A and the second area 5B on the main surface of thesemiconductor chip 5 to electrically separate the first area 5A and thesecond area 5B from each other. In the third area 5C, a chip-sidebonding electrode 6C is formed at a location in close proximity to theside 5X of the semiconductor chip 5 and a chip-side bonding electrode 6Fis formed at a location in close proximity to the side 5Y of thesemiconductor chip 5.

The chip-side input electrode 6A is electrically connected by an inputwire 7A to a substrate-side input electrode 2A which is formed on themain surface of the wiring substrate 1 to face the side SX of thesemiconductor chip 5. The substrate-side input electrode 2A iselectrically connected to the input external terminal Pin formed on theback surface of the wiring substrate 1 by an internal wire and athrough-hole wire 3 bored at a location right below the substrate-sideinput electrode 2A.

The chip-side output electrode 6B is electrically connected by an outputwire 7B to a substrate-side output electrode 2B which is formed on themain surface of the wiring substrate 1 to face the side 5X of thesemiconductor chip 5. The substrate-side output electrode 2B iselectrically connected by an internal wire and a through-hole wire 3bored at a location right below the substrate-side output electrode 2Bto a substrate input terminal formed on the main surface of the wiringsubstrate 1 to face a side of the other semiconductor chip for creatingthe amplifying means PW3.

The chip-side bonding electrode 6C is electrically connected by a wire7C to a substrate-side bonding electrode 2C which is formed on the mainsurface of the wiring substrate 1 to face the side 5X of thesemiconductor chip 5. The substrate-side bonding electrode 2C iselectrically connected by an internal wire and a through-hole wire 3bored at a location right below the substrate-side bonding electrode 2Cto the reference-potential external terminal 4 (FIG. 4) formed on theback surface of the wiring substrate 1. In such an arrangement, the wire7C is thus set at a fixed reference electric potential.

The chip-side output electrode 6D is electrically connected by an outputwire 7D to a substrate-side output electrode 2D which is formed on themain surface of the wiring substrate 1 to face the other side 5Y of thesemiconductor chip 5. A through-hole wire 3 is bored at a location rightbelow the substrate-side output electrode 2D.

The chip-side input electrode 6E is electrically connected by an inputwire 7E to a substrate-side input electrode 2E which is formed on themain surface of the wiring substrate 1 to face the other side 5Y of thesemiconductor chip 5. The substrate-side input electrode 2E iselectrically connected by an internal wire and a through-hole wire 3 tothe substrate-side output electrode 2D.

The chip-side bonding electrode 6F is electrically connected by a wire7F to a substrate-side bonding electrode 2F which is formed on the mainsurface of the wiring substrate 1 to face the other side 5Y of thesemiconductor chip 5. The substrate-side bonding electrode 2F iselectrically connected by an internal wire and a through-hole wire 3bored at a location right below the substrate-side bonding electrode 2Fto the reference-potential external terminal 4 formed on the backsurface of the wiring substrate 1. In such an arrangement, the wire 7Fis thus set at a fixed reference electric potential.

The distance between the chip-side output electrode 6D and the otherside 5Y of the semiconductor chip 5 is shorter than the distance betweenthe chip-side input electrode 6A and the side 5X of the semiconductorchip 5. In addition, the distance between the chip-side output electrode6B and the side 5X of the semiconductor chip 5 is shorter than thedistance between the chip-side input electrode 6E and the other side 5Yof the semiconductor chip 5. In this way, the output wires are eachshort to give a small output resistance.

A source electrode 6S electrically connected to the source terminal ofthe amplifying means PW1 is formed on the first area 5A of the mainsurface of the semiconductor chip 5. The source electrode 6S is placedat a location in closer proximity to the side 5X of the semiconductorchip 5 than the chip-side input electrode 6A is. A source electrode 6Selectrically connected to the source terminal of the amplifying meansPW2 is formed on the second area 5B of the main surface of thesemiconductor chip 5. These source electrodes 6S are used for probeinspection.

In the high-frequency power amplifier implemented by this embodiment,the input wire 7A and the output wire 7B are placed at locations closeto each other. The input wire 7A is electrically connected to the gateterminal (serving as the input unit) of the amplifying means PW1 and theoutput wire 7B is electrically connected to the drain terminal (servingas the output unit) of the amplifying means PW2. Thus, a differencebetween a power flowing through the input wire 7A and a power flowingthrough the output wire 7B is big. Since the wire 7C set at a fixedreference electric potential is placed between the input wire 7A and theoutput wire 7B, however, it is possible to prevent the high-frequencycharacteristic from deteriorating due to a mutual-induction effectbetween the input wire 7A and the output wire 7B.

Further, the output wire 7D and the input wire 7E are placed atlocations close to each other. The output wire 7D is electricallyconnected to the drain terminal (serving as the output unit) of theamplifying means PW1 and the input wire 7E is electrically connected tothe gate terminal (serving as the input unit) of the amplifying meansPW2. Thus, the magnitude of a power flowing through the output wire 7Dis about equal to the magnitude of a power flowing through the inputwire 7E. As a result, the high-frequency characteristic deterioratesonly a little due to a mutual-induction effect between the output wire7D and the input wire 7E. In addition, since the wire 7F set at a fixedreference electric potential is placed between the output wire 7D andthe input wire 7E, it is possible to prevent the high-frequencycharacteristic from further deteriorating due to the mutual-inductioneffect between the output wire 7D an the input wire 7E.

The substrate-side bonding electrode 2C is placed at a location fartherfrom the side 5X of the semiconductor chip 5 than the substrate-sideoutput electrode 2B. The substrate-side input electrode 2A is placed atabout the same distance from the side 5X of the semiconductor chip 5 asthe substrate-side output electrode 2B. Thus, the substrate-side bondingelectrode 2C is placed not between the substrate-side input electrode 2Aand the substrate-side output electrode 2B but at a location fartherfrom the side 5X of the semiconductor chip 5 than the substrate-sideinput electrode 2A and the substrate-side output electrode 2B. As aresult, a gap between the substrate-side input electrode 2A and thesubstrate-side output electrode 2B can be made narrower by an amountcorresponding to the size of an area occupied by the substrate-sidebonding electrode 2C. Accordingly, a gap between the first area 5A andthe second area 5B of the semiconductor chip 5 can also be narrowed aswell, allowing the area occupied by the semiconductor chip 5 to beshrunk.

Further, the substrate-side bonding electrode 2F is placed at a locationfarther from the other side 5Y of the semiconductor chip 5 than thesubstrate-side output electrode 2D. The substrate-side input electrode2E is placed at about the same distance from the other side 5Y of thesemiconductor chip 5 as the substrate-side output electrode 2D. Thus,the substrate-side bonding electrode 2F is placed not between thesubstrate-side input electrode 2E and the substrate-side outputelectrode 2D but at a location farther from the other side 5Y of thesemiconductor chip 5 than the substrate-side input electrode 2E and thesubstrate-side output electrode 2D. As a result, a gap between thesubstrate-side input electrode 2E and the substrate-side outputelectrode 2D can be made narrower by an amount corresponding to the sizeof an area occupied by the substrate-side bonding electrode 2F.Accordingly, a gap between the first area 5A and the second area 5B ofthe semiconductor chip 5 can also be narrowed as well, allowing the areaoccupied by the semiconductor chip 5 to be shrunk.

As shown in FIG. 6, the semiconductor chip 5 has a configurationincluding a semiconductor substrate 10 as a main component. Thesemiconductor substrate 10 comprises a p+ semiconductor substrate 10Aand a p− epitaxial layer 10B formed on the main surface of the p+semiconductor substrate 10A which is typically made ofmonolithic-crystal silicon.

Field-effect transistors constituting the amplifying means PW1 and PW2are formed in a transistor formation area on the main surface of thesemiconductor substrate 10. The field-effect transistors each comprisemainly a p well area 12 used as a channel formation area, a gateinsulation film 14, a gate electrode 15 and a pair of an n-semiconductorarea 16 and an n+ semiconductor area 17 serving as a source area and adrain area.

The n+ semiconductor area 17 serving as a drain area is electricallyconnected to a wire 19A formed on a first wiring layer by a connectionhole bored through an interlayer insulation film 18. The n+semiconductor area 17 serving as a source area is electrically connectedto a wire 19B formed on the first wiring layer by a connection holebored through the interlayer insulation film 18. The wire 19B iselectrically connected to a p+ semiconductor area 13 formed on a p typeepitaxial layer 13 by a connection hole bored through the interlayerinsulation film 18. The p+ semiconductor area 13 is electricallyconnected to the p+ semiconductor substrate 10A. The gate electrode 15is electrically connected to a wire 19C formed on the first wiring layerby a connection hole bored through the interlayer insulation film 18. Itshould be noted that this connection is not shown in detail in thefigure.

The wire 19A is electrically connected to a wire 21A formed on a secondwiring layer by a connection hole bored through an interlayer insulationfilm 20. Portions of the wire 21A are formed on the chip-side outputelectrode 6D and the chip-side output electrode 6B. The wire 19B iselectrically connected to a wire 21B formed on the second wiring layerby a connection hole bored through the interlayer insulation film 20.Portions of the wire 21B are formed on the electrodes used for probeinspection. The wire 19C is electrically connected to a wire formed onthe second wiring layer by a connection hole bored through theinterlayer insulation film 20. It should be noted that this connectionis not shown in the figure. Portions of the wire are formed on thechip-side input electrode 6A and the chip-side input electrode 6E.

In the third area 5C of the semiconductor chip 5, a wire 19D formed onthe first wiring layer is formed on a field insulation film 11 as shownin FIG. 7. The wire 19D is extended in a direction perpendicular to theside 5X of the semiconductor chip 5. The wire 19D is electricallyconnected to a wire 21D formed on the second wiring layer by aconnection hole bored through the interlayer insulation film 20. Muchlike the wire 19D, the wire 21D is extended in a direction perpendicularto the side 5X of the semiconductor chip 5. Portions of the wire 21D areformed on the chip-side bonding electrode 6C and the chip-side bondingelectrode 6F.

A back-surface electrode 21 is formed on the other main surface (or theback surface) facing the main surface of the semiconductor substrate 10cited earlier. The back-surface electrode 21 is electrically andmechanically connected to the conductive plate 1B formed on the bottomof the dent 1A of the wiring substrate 1. In such an arrangement, thesource terminals of the amplifying means PW1 and PW2 are thus set at thefixed reference electric potential.

In the high-frequency power amplifier implemented by this embodiment,the wires 19D and 21D set at a fixed reference electric potential arestretched in a direction perpendicular to the side 5X of thesemiconductor chip 5 in the third area 5C (used as an isolation area)between the first area 5A and the second area 5B of the semiconductorchip 5. In addition, the p+ semiconductor area 13 set at the fixedreference electric potential is also stretched in a directionperpendicular to the side 5X of the semiconductor chip 5 in the thirdarea 5C. Moreover, the semiconductor substrate 10 is also set at thefixed reference electric potential. As a result, the semiconductor chip5 has a configuration in which magnetic-flux interference is suppressedso that the high-frequency characteristic will not deteriorate by allmeans.

According to the embodiment described above, the following effects areexhibited.

(1) Since the substrate-side bonding electrode 2C is placed at alocation farther from the side 5X of the semiconductor chip 5 than thesubstrate-side input electrode 2A and the substrate-side outputelectrode 2B are whereas the substrate-side bonding electrode 2F isplaced at a location farther from the other side 5Y of the semiconductorchip 5 than the substrate-side input electrode 2E and the substrate-sideoutput electrode 2D are, a gap between the substrate-side inputelectrode 2A and the substrate-side output electrode 2B can be madenarrower by an amount corresponding to the size of an area occupied bythe substrate-side bonding electrode 2C. Further, a gap between thesubstrate-side input electrode 2E and the substrate-side outputelectrode 2D can be made narrower by an amount corresponding to the sizeof an area occupied by the substrate-side bonding electrode 2F.Accordingly, a gap between the first area 5A and the second area 5B ofthe semiconductor chip 5 can also be narrowed as well. As a result,since the area occupied by the semiconductor chip 5 can be shrunk, thehigh-frequency power amplifier can be made smaller in size.

(2) Since the substrate-side input electrode 2A is placed at about thesame distance from the side 5X of the semiconductor chip 5 as thesubstrate-side output electrode 2B whereas the substrate-side bondingelectrode 2C is placed at a location farther from the side 5X of thesemiconductor chip 5 than the substrate-side input electrode 2A and thesubstrate-side output electrode 2B, the wire 7C set at a fixed referenceelectric potential crosses a gap between the substrate-side inputelectrode 2A and the substrate-side output electrode 2B. As a result,magnetic-flux interference can be further suppressed in comparison witha case in which the substrate-side bonding electrode 2C is placedbetween the substrate-side input electrode 2A and the substrate-sideoutput electrode 2B.

It should be noted that, in this embodiment, the wires 7C and 7F are setat a fixed reference electric potential as described above. In addition,since the magnitude of a power flowing through the output wire 7Dconnected to the drain terminal (serving as the output unit) of theamplifying means PW1 at the front stage is about equal to the magnitudeof a power flowing through the input wire 7E connected to the gateterminal (serving as the input unit) of the amplifying means PW2 at thelater stage, it is not necessary to specially provide a wire set at afixed reference electric potential between the output wire 7D and theinput wire 7E. In this case, the chip-side bonding electrode 6F and thesubstrate-side bonding electrode 2F are therefore not required.

In addition, in this embodiment, the substrate-side input electrode 2Ais placed at about the same distance from the side 5X of thesemiconductor chip 5 as the substrate-side output electrode 2B asdescribed above. It should be noted that the substrate-side inputelectrode 2A can also be placed at a location farther from the side 5Xof the semiconductor chip 5 than the substrate-side bonding electrode2C. In such an arrangement, the same effects as the embodiment areexhibited. In this case, however, since the input wire 7A becomeslonger, the high-frequency characteristic deteriorates to a certaindegree.

Second Embodiment

FIG. 8 is a diagram showing a top view of principal parts of a wiringsubstrate of a high-frequency power amplifier implemented by a secondembodiment of the present invention.

The high-frequency power amplifier implemented by the second embodimentbasically has the same configuration as the first embodiment except forthe following differences.

As shown in FIG. 8, the substrate-side bonding electrode 2C iselectrically and mechanically connected to one end of a wire 7Gstretched over the third area 5C of the semiconductor chip 5 and thesubstrate-side bonding electrode 2F is electrically and mechanicallyconnected to the other end of the wire 7C. Since the substrate-sidebonding electrode 2C and the substrate-side bonding electrode 2F areelectrically connected to the reference-potential external terminal 4,the wire 7G is set at the fixed reference electric potential.

Since the substrate-side bonding electrodes 2C and 2F are electricallyand mechanically connected the ends of the wire 7G as described above,it is possible to prevent the high-frequency characteristic fromdeteriorating due to a mutual-induction effect between the input wire 7Aand the output wire 7B and a mutual-induction effect between the outputwire 7D and the input wire 7E.

Third Embodiment

FIG. 9 is a diagram showing a top view of principal parts of a wiringsubstrate of a high-frequency power amplifier implemented by a thirdembodiment of the present invention.

The high-frequency power amplifier implemented by the third embodimentbasically has the same configuration as the first embodiment except forthe following differences.

As shown in FIG. 9, the amplifying means PW1, PW2 and PW3 are formed ona single semiconductor chip 5. The amplifying means PW3 is formed in afourth area 5D of the main surface of the semiconductor chip 5.

Formed in the fourth area 5D of the main surface of the semiconductorchip 5, the gate terminal (serving as the input unit) of the amplifyingmeans PW3 is electrically connected to a chip-side input electrode 6H inclose proximity to the side 5X (a long side in the case of thisembodiment) of the semiconductor chip 5. Formed in the fourth area 5D ofthe main surface of the semiconductor chip 5, the drain terminal(serving as the output unit) of the amplifying means PW3 is electricallyconnected to a chip-side output electrode 6K in close proximity to theother side 5Y (another long side in the case of this embodiment) of thesemiconductor chip 5 facing the side 5X. Much like the amplifying meansPW1, the source terminal of the amplifying means PW3 is electricallyconnected to a back-surface electrode 21 formed on a back surface of thesemiconductor chip 5.

A fifth area 5E (serving as an isolation area) is formed between thefourth area 5D and the second area 5B on the main surface of thesemiconductor chip 5 to electrically separate the fourth area 5D and thesecond area 5B from each other.

The chip-side input electrode 6H is electrically connected by a wire 7Hto a substrate-side input electrode 2H which is formed on the mainsurface of the wiring substrate 1 to face the side 5X of thesemiconductor chip 5. The substrate-side input electrode 2H iselectrically connected by an internal wire and a through-hole wire 3bored at a location right below the substrate-side input electrode 2H tothe substrate-side output electrode 2B.

The chip-side output electrode 6K is electrically connected by a wire 7Kto a substrate-side output electrode 2K which is formed on the mainsurface of the wiring substrate 1 to face the other side 5Y of thesemiconductor chip 5. The substrate-side output electrode 2K iselectrically connected by an internal wire and a through-hole wire 3bored at a location right below the substrate-side bonding electrode 2Fto the output external terminal formed on the back surface of the wiringsubstrate 1.

A substrate-side bonding electrode 2J is formed on the main surface ofthe wiring substrate 1 to face the side 5X of the semiconductor chip 5.On the other hand, a substrate-side bonding electrode 2L is formed onthe main surface of the wiring substrate 1 to face the side 5Y of thesemiconductor chip 5. Much like the substrate-side bonding electrode 2C,the substrate side bonding electrodes 2J and 2L are electricallyconnected to the reference-potential terminal 4 formed on the backsurface of the wiring substrate 1.

The substrate-side bonding electrode 2J is placed at about the samedistance from the side 5X of the semiconductor chip 5 as thesubstrate-side bonding electrode 2C. On the other hand, thesubstrate-side bonding electrode 2L is placed at about the same distancefrom the other side 5Y of the semiconductor chip 5 as the substrate-sideoutput electrode 2F.

The substrate-side bonding electrode 2J is electrically and mechanicallyconnected to one end of a wire 7L stretched over the fifth area 5E ofthe semiconductor chip 5 and the substrate-side bonding electrode 2L iselectrically and mechanically connected to the other end of the wire 7L.

In the high-frequency power amplifier implemented by this embodiment,two wires 7L are provided. A difference between a power flowing throughthe input wire 7E and a power flowing through the output wire 7K islarger than a difference between a power flowing through the input wire7A and a power flowing through the output wire 7B. By increasing thenumber of wires set at the fixed reference electric potential inaccordance with the difference in power as is the case with thisembodiment, it is possible to prevent the high-frequency characteristicfrom deteriorating due to a mutual-induction effect between an inputwire and an output wire in a more stable state.

Fourth Embodiment

FIG. 10 is a diagram showing a top view of principal parts of a wiringsubstrate of a high-frequency power amplifier implemented by a fourthembodiment of the present invention.

The high-frequency power amplifier implemented by the fourth embodimentbasically has the same configuration as the first embodiment except forthe following differences.

As shown in FIG. 10, the substrate-side output electrode 2B is placed ata location facing the side 5X of the semiconductor chip 5 while thesubstrate-side input electrode 2A is placed at a location facing anotherside 5P crossing the side 5X of the semiconductor chip 5.

Since the substrate-side output electrode 2B is placed at a locationfacing the side 5X of the semiconductor chip 5 while the substrate-sideinput electrode 2A is placed at a location facing the other side 5Pcrossing the side 5X of the semiconductor chip 5 as described above, amagnetic flux of the input wire 7A perpendicularly crosses a magneticflux of the output wire 7B. As a result, a mutual-induction effectbetween the input wire 7A and the output wire 7B is suppressed.

In addition, since it is not necessary to provide a substrate-sidebonding electrode for connecting a wire set at the fixed referenceelectric potential, a gap between the first area 5A and the second area5B of the semiconductor chip 5 can be narrowed. Thus, the area occupiedby the semiconductor chip 5 can be shrunk. As a result, thehigh-frequency power amplifier can be made smaller in size.

Fifth Embodiment

As shown in FIG. 15, the present invention provides couplingcoefficients smaller than those of the conventional technology,improving the high-frequency characteristic. In addition, for couplingcoefficients not exceeding 0.12 (or for coefficients of stabilitygreater than 1), a range of the distance d between bonding portionsbecomes wider, raising the degree of design freedom. Moreover, thedistance d between bonding portions can be decreased to 0.3 mm, allowingthe chip area to be made smaller. As a result, the high-frequency poweramplifier module can be made small in size and the cost thereof can bereduced.

FIG. 15 shows a case in which an angle ø formed by an input bonding wireand an output bonding wire is set at 90 degrees. As shown in FIG. 17,the angle ø can be set at a value in the range 72 degrees to 180degrees. At an angle ø of 140 degrees, the coupling coefficient is equalto a minimum. It is thus obvious that a local minimum point exists.

In the actual design of a high-frequency power amplifier module providedby the present invention, a distance d between bonding portions and theangle ø are selected on the basis of the above consideration.

In addition, as is obvious from the above description, to set the angleø at a value other than 0 degrees is the basis underlying the presentinvention. Thus, a high-frequency power amplifier module can be designedto give a coefficient of stability of at least 1 for twoamplifying-stage transistors associated with input and output bondingwires by setting the angle ø at a value in the range 72 degrees to 180degrees.

A two-stage power amplifier module provided by the fifth embodiment ofthe present invention is explained below by referring to FIGS. 11 to 14.FIG. 11 is a diagram showing a top view of principal parts of thetwo-stage power amplifier module and FIG. 12 is a diagram showing anequivalent circuit of the two-stage power amplifier module. FIG. 13 is adiagram showing a top view of an external configuration of the two-stagepower amplifier module and FIG. 14 is a diagram showing a perspectiveview of principal parts of the two-stage power amplifier module.

As shown in FIG. 11, transistors 102 and 103 each implemented by aMOSFET at the first and second stages respectively are formed on asilicon chip 101 at locations close to each other. The transistors 102and 103 are laid out so that the direction of a high-frequency signalflowing from the gate electrode 102 a of the first-stage transistors 102to the drain electrodes 102 b thereof is opposite to the direction of ahigh-frequency signal flowing from the gate electrodes 103 a of thesecond-stage transistors 103 to the drain electrodes 103 b thereof.

The gate electrode 102 a serving as the high-frequency input terminal isconnected to a terminal 121 of an input matching circuit 125 on a wiringsubstrate 113 by one input bonding wire 105. On the other hand, thedrain electrodes 103 b serving as the high-frequency output terminal areconnected to a terminal 124 of an output matching circuit 127 on thewiring substrate 113 by four output bonding wires 108. The gateelectrode 102 a is placed at a location in close proximity to the leftside of the silicon chip 101 whereas the drain electrodes 103 b areplaced at locations in close proximity to the upper side of the siliconchip 101. An angle formed by the input bonding wire 105 and the outputbinding wires 108 is thus about 90 degrees. The drain electrodes 102 bare connected to a terminal 122 of an interstage matching circuit 126 onthe wiring substrate 113 by bonding wires 106. On the other hand, thegate electrodes 103 a are connected to a terminal 123 of the interstagematching circuit 126 by bonding wires 107. The distance between thebonding portion of the gate electrode 102 a (or the bonding inputelectrode) of the first-stage transistors 102 and the bonding portion ofthe drain electrodes 103 b (or the bonding output electrodes) of thesecond-stage transistors 103 is about 0.6 mm.

The silicon chip 101 is mounted in a cavity 104 formed on the wiringsubstrate 113. Metallic films serving as the source electrodes of thefirst-stage and second-stage transistors 102 and 103 are attached to theback surface of the silicon chip 101 and connected to the electricpotential of the ground by wires in the cavity 104. The wiring substrate113 is made of a dielectric material such as glass ceramics or alumina.On the other hand, wires in the wiring substrate 113 are made of copper,silver or silver platinum.

In FIGS. 12 and 13, notations P_(in), P_(out), V_(gg) and V_(dd) denotea high-frequency signal input terminal, a high-frequency outputterminal, a gate-voltage applying terminal and a drain-voltage applyingterminal respectively which are each an external connection terminal ofthe power amplifier module. In FIG. 13, a hatched line indicates aboundary between the input matching circuit 125 and the interstagematching circuit 126 or a boundary between the interstage matchingcircuit 126 and the output matching circuit 127. FIG. 14 is a diagramshowing a 3-dimensional structure of parts surrounding the cavity 104.

In this embodiment, an angle formed by the input bonding wire 105 andthe output binding wires 108 is set at about 90 degrees as describedabove. It should be noted, however, that this angle can be set at anyvalue in the range 72 degrees to 180 degrees.

Sixth Embodiment

A three-stage power amplifier module implemented by a sixth embodimentof the present invention is explained by referring to a diagram of FIG.18 showing a top view of principal parts thereof. As shown in thefigure, transistors 102, 103 and 114 each implemented by a MOSFET at theinput, intermediate and output stages respectively are formed on asilicon chip 101 at locations close to each other. The transistors 102and 103 are laid out so that the direction of a high-frequency signalflowing from the gate electrode 102 a of the input-stage transistors 102to the drain electrodes 102 b thereof is opposite to the direction of ahigh-frequency signal flowing from the gate electrodes 103 a of theintermediate-stage transistors 103 to the drain electrodes 103 bthereof. Further, the transistors 103 and 114 are laid out so that thedirection of a high-frequency signal flowing from the gate electrode 103a of the intermediate-stage transistors 103 to the drain electrodes 103b thereof is opposite to the direction of a high-frequency signalflowing from the gate electrodes 114 a of the output-stage transistors114 to the drain electrodes 114 b thereof.

The sixth embodiment is different from the fifth embodiment in that, inthe case of the former, the present invention is applied as follows. Anangle formed by the input bonding wire 105 of the input-stagetransistors 102 and the output binding wires 108 of theintermediate-stage transistors 103 is set at about 140 degrees; thetransistors 114 at the output stage are provided on the same chip; anangle formed by the output bonding wires 110 of the output-stagetransistors 114 and the input binding wires 107 of theintermediate-stage transistors 103 is set at about 90 degrees; and thedistance d between the bonding portion of the gate electrodes 103 a (orthe bonding input electrodes) of the intermediate-stage transistors 103and the bonding portion of the drain electrodes 114 b (or the bondingoutput electrodes) of the output-stage transistors 114 is about 0.7 mm.

According to this embodiment, a coupling coefficient between the inputbonding wire 105 of the input-stage transistors 102 and the outputbonding wires 108 of the intermediate-stage transistors 103 can bereduced to a minimum as shown in FIG. 17, allowing isolation between theinput bonding wire 105 and the output bonding wires 108 to be furtherimproved. In addition, since the present invention is applied, isolationbetween the input bonding wires 107 of the intermediate-stagetransistors 103 and the output bonding wires 109 of the output-stagetransistors 114 can be assured as well. As a result, in the case of thesixth embodiment wherein transistors at three-stages are formed on thesame chip in order to shrink the area of the semiconductor chip, thehigh-frequency characteristic can be improved in spite of the fact thatdistances between transistors are shorter.

Seventh Embodiment

A three-stage power amplifier module implemented by a seventh embodimentof the present invention is explained by referring to a diagram of FIG.19 showing a top view of principal parts thereof. The seventh embodimentis different from the sixth embodiment in that, in the case of theformer, a shield bonding wire 201 and a shield wire 204 are providedbetween an intermediate-stage transistor 103 and an output-stagetransistor 114 by applying a shield technology, and one end of theshield bonding wire 201 and one end of the shield wire 204 are eachconnected to the electric potential of the ground by an electrode 202and a via hole 203 formed on the wiring substrate.

In this embodiment, the conventional shield technology is applied to agap between the input and intermediate stages. Since the sizes of theareas of the transistors at the input and intermediate stages are largefrom the beginning, however, the high-frequency characteristic can beimproved.

Eighth Embodiment

A two-stage power amplifier module implemented by an eighth embodimentof the present invention is explained by referring to a diagram of FIG.20 showing a top view of principal parts thereof.

The eighth embodiment is different from the fifth embodiment in that, inthe case of the former, the orientation of the first-stage transistors102 is rotated by 90 degrees.

In this embodiment, since the locations of the bonding portions of theinput bonding wire 105 at the first stage and the output bonding wires108 at the second stage are moved to the center of the chip, thedistance between the bonding portions can be made even longer. (In thecase of the first embodiment, the distance is 0.6 mm. In the case of theeighth embodiment, on the other hand, the distance is 0.75 mm). As aresult, the isolation between the input bonding wire 105 at the firststage and the output bonding wires 108 at the second stage can befurther improved.

Preferred embodiments of the present invention have been explained sofar. It should be noted, however, that the scope of the presentinvention is not limited to the embodiments. For example, parameterssuch as the number of electrodes of transistors and the number ofbonding wires can be changed to a variety of values in dependence on theapplication without deviating from the gist of the present invention. Inaddition, the transistors do not have to be each implemented by aMOSFET, but they can also be each implemented by a field-effecttransistor or a hetero-junction bipolar transistor (HBT).

1. An RF power amplifier module including a power amplifier circuit,said RF power amplifier module comprising: a semiconductor chip having amain surface, said main surface being quadrilateral and having a pair offirst sides and a pair of second sides perpendicular to the first sides;a mounting substrate having a mounting surface over which saidsemiconductor chip is mounted; an input stage transistor having a firstinput node and a first output node, disposed on the main surface of thesemiconductor chip; an intermediate stage transistor having a secondinput node and a second output node, disposed on the main surface of thesemiconductor chip, said first output node being electrically coupled tothe second input node; an output stage transistor having a third inputnode and a third output node, disposed on the main surface of thesemiconductor chip, said second output node being electrically coupledto the third input node, said input stage, intermediate stage and outputstage transistors comprising the power amplifier circuit; an inputterminal disposed on the mounting surface of the mounting substrate; anoutput terminal disposed on the mounting surface of the mountingsubstrate; an input bonding wire electrically coupling the inputterminal and the first input node, said input bonding wire beingdisposed so as to cross over one of the first sides of the main surfaceof the semiconductor chip; and an output bonding wire electricallycoupling the output terminal and the third output node, said outputbonding wire being disposed so as to cross over one of the second sidesof the main surface of the semiconductor chip.
 2. An RF power amplifiermodule according to claim 1, wherein the input terminal is disposedalong the one first side of the main surface of the semiconductor chip.3. An RF power amplifier module according to claim 1, wherein the outputterminal is disposed along the one second side of the main surface ofthe semiconductor chip.
 4. An RF power amplifier module according toclaim 1, wherein the input stage, intermediate stage and output stagetransistors are hetero-junction bipolar transistors (HBT).
 5. An RFpower amplifier module according to claim 1, wherein a capacitiveelement and a resistive element are disposed on the mounting surface ofthe mounting substrate; and said capacitive element and a resistiveelement are electrically coupled to the input terminal.
 6. An RF poweramplifier module according to claim 1, wherein a capacitive element anda resistive element are disposed on the mounting surface of the mountingsubstrate; and said capacitive element and resistive element areelectrically coupled to the output terminal.
 7. An RF power amplifiermodule according to claim 1, wherein the mounting substrate has a backsurface opposite to the mounting surface; a plurality of externalelectrodes are disposed on the back surface; one of the externalelectrodes is electrically coupled to the input terminal; and anotherone of the external electrodes is electrically coupled to the outputterminal.
 8. An RF power amplifier module according to claim 1, whereinthe mounting substrate is comprised of laminated insulating layers. 9.An RF power amplifier module including a power amplifier circuit, saidRF power amplifier module comprising: a semiconductor chip having a mainsurface; a mounting substrate having a mounting surface over which saidsemiconductor chip is mounted; an input stage transistor having a firstinput node and a first output node, disposed on the main surface of thesemiconductor chip; an intermediate stage transistor having a secondinput node and a second output node, disposed on the main surface of thesemiconductor chip, said first output node being electrically coupled tothe second input node; an output stage transistor having a third inputnode and a third output node, disposed on the main surface of thesemiconductor chip, said second output node being electrically coupledto the third input node, said input stage, intermediate stage and outputstage transistors comprising the power amplifier circuit; an inputterminal disposed on the mounting surface of the mounting substrate; anoutput terminal disposed on the mounting surface of the mountingsubstrate; an input bonding wire electrically coupling the inputterminal and the first input node; and an output bonding wireelectrically coupling the output terminal and the third output node. 10.An RF power amplifier module according to claim 9, wherein the inputterminal is disposed along the one first side of the main surface of thesemiconductor chip.
 11. An RF power amplifier module according to claim9, wherein the output terminal is disposed along the one second side ofthe main surface of the semiconductor chip.
 12. An RF power amplifiermodule according to claim 9, wherein the input stage, intermediate stageand output stage transistors are hetero-junction bipolar transistors(HBT).
 13. An RF power amplifier module according to claim 9, wherein acapacitive element and a resistive element are disposed on the mountingsurface of the mounting substrate; and said capacitive element and aresistive element are electrically coupled to the input terminal.
 14. AnRF power amplifier module according to claim 9, wherein a capacitiveelement and a resistive element are disposed on the mounting surface ofthe mounting substrate; and said capacitive element and resistiveelement are electrically coupled to the output terminal.
 15. An RF poweramplifier module according to claim 9, wherein the mounting substratehas a back surface opposite to the mounting surface; a plurality ofexternal electrodes are disposed on the back surface; one of theexternal electrodes is electrically coupled to the input terminal; andanother one of the external electrodes is electrically coupled to theoutput terminal.
 16. An RF power amplifier module according to claim 9,wherein the mounting substrate is comprised of laminated insulatinglayers.